Polar vortex: It's baaaaack!

Here's what it is and why you should pay attention when it arrives.

Is cold, snowy weather in your local forecast?
(Photo: Scharfsinn/Shutterstock)

Meteorology and climate are complex topics, so it's easy to be confused about certain weather terms. You may have heard about the super-cold weather forecast for much of the country next week, including references to the "polar vortex." But is that dramatic moniker a name the media made up, or is it a legit thing? And what does it mean, if anything, for the rest of the winter (and coming years)?

According to the National Weather Service (NWS), the polar vortex is a "large area of low pressure and cold air surrounding both of the Earth’s poles. It always exists near the poles, but ... strengthens in winter. The term 'vortex' refers to the counter-clockwise flow of air that helps keep the colder air near the poles. Many times during winter in the Northern Hemisphere, the polar vortex will expand, sending cold air southward with the jet stream."

The last time the United States felt the chilling impact of the polar vortex was January 2014, when the Midwest saw its coldest weather in nearly 20 years with wind chills as low as 50 degrees below zero; nine people died as a result. Several notable colder outbreaks happened in 1977, 1982, 1985 and 1989, the NWS notes. So while the polar vortex is not a new phenomenon, the term has gained popularity fairly recently.

The 2016 polar vortex

Current forecasts say cold weather will hit the Midwest and Northeast starting around Dec. 13, with some cities like Chicago facing temps in the teens while Minnesota and North Dakota brace for single digits, according to AccuWeather.

Looking at a few cities 10-day forecasts from ECMWF 12z. Bismarck ND coldest -32°F w/a daily high of -20°F pic.twitter.com/esgWlYfUWA

The video below explains more about how the polar vortex works and includes graphics that may help you visualize it better:

The NWS says there's no cause for alarm when a polar vortex is expected. Be prepared for cold temperatures, bundle up with coats and hats and other cold weather gear if you go outside, and consider restocking or checking your emergency kits at home before the coldest weather arrives, they suggest.

Editor's note: This story has been updated since it was originally published in January 2014.

Angela Nelson ( @bostonangela ) is an exhausted mom of two young daughters and two old cats, and a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide.